Distillation of tar



:s sheets-sheet 1 S. F. MILLER DISTILLATION OF' TAR Original Filed Dec.

May l5, 1934.

NVENTOR ifm ATToRNEY May 15, 1934. s. P. MILLER DISTILLATION OF TAROriginal Filed Dec. 1l, 1929 3 Sheets-Sheet 2 Fig .JL/ Hrm ya INVENTQR5, PM BY @@wg f M ATTORNEY5 May 15, 1934. s. P. MILLER DISTILLATION OFTAR originan Filed Dec. 5 sheets-sheet s l Patented. May 15, 1934 UNITEDSTATES y,PATENT OFFICE to The Barrett Company, New York, N. Y

corporation of New Jersey Application Decemberll, 1929, Serial No.413,252

Renewed December 14, 1933 n 7 Claims. (Cl. 202-30) This inventionrelates to the distillation of tar by direct contact with the hot gasesfrom a plurality of gas retorts. The hot gases from a number of retortsare collected togetherand passed into a still, the tar to be distilledis brought into direct contact with the hot gases in the still and pitchis produced. The invention includes both the process and apparatus forcarrying it out.

In a gas retort plant such as a horizontal gas 10 retort plant, theretorts are ordinarily arranged in tiers with four to six or moreretorts in each tier. A single vertical pipe called a multiple standpipeis often employed to collect thegases from all of the retorts in onetier or from all of the retorts in two adjacent tiersjand to conveythese combined gases to the hydraulic main or other gas collector main.According to this invention a multiple standpipe, which may .be similarto the usual standpipe, is employed, but the standpipe of this inventionis heavly insulated and the gases are conveyed to a still and employedfor the distillation of tar. The gases from several such standpipes mayadvantageously be combined and conveyed to one or more stills, which maybe located on top of the gas retort bench or adjacent thereto. 'Ihegases from all'of the retorts in a tier or all of the retorts in twoadjacent tiers are collected in a single standpipe and the gases from anumber of retorts are supplied to a single still and employed for thedistillation of tar in this still. The pipes connecting the still withthe retortsand the still itself are heavily insulated so that the gasesenter the still at a high temperature approaching the temperature atwhich they leave the retorts.

The temperature and quantity of the gases generated in a retort varyduring the distillation of a single charge of coal in the retort. Alarge quantity of gases of relatively lower temperature are evolvedduring the earlier stages of the distillation, and during the laterstages less gases, but gases of higher temperature are evolved. Bycombining the gases from several retorts charged at intervals, andpreferably charged in rotation so that no two retorts are charged at thesame time but the time between the charging of any two or more of theretorts is substantially the same, gases of relatively constanttemperature are obtained and in relatively uniform quantities. Accordingto this invention the gases from a number of retorts are combined andthe heat of the combined gases is employed for the distillation of tarby bringing the tar into direct contact with the hot gases.

Several stills may be provided each connected with the retorts inseveral tiers.v The tar may be partially distilled in each of thestills, and by being passed through a number of the stills in series apitch of any desired melting point may be obtained. Where several stillsare thus employed in series a portion of the partially distilled tarproduced in any one of the stills preceding the nal still may be drawn01T as a separate intermediate product. The gases and vapors from all ofthe stills may be combined and treated in the same condensing system toproduce a desired total oil or several oil fractions, as desired.Instead of employing a single condensing system an individual condenseror partial condensers may be connected with one or more of the stills inthe series to separately collect an oil fraction from any selectedstill.

Instead of operating the stills in series fresh tar may be supplied toeach of the stills so that the stills are operated in parallel and theoperation may be so controlled as to produce any desired oil or pitchproducts.' One condensing system may be connected with all of the stillsso that one total oil or several oil fractions are collected from thecombined gases and vapors resulting from the distillation in all of thestills. Where desirable a separate condenser or a separate partialcondenser may be connected with any one or all of the stills to separateone or more desired clean oil fractions from the gases.

The hot gases and vapors leaving the stills are advantageously employedfor preheating the tar to be distilled. A single tar preheater may beprovided through which the combined gases and vapors from all of thestills pass. In this Way a clean oil, comprising constituents present inthe gases and vapors leaving each of the ovens will be obtained in theheat interchanger. By connecting a preheater with any one or more of thestills individually, one or more tar oil fractions may be separatelycondensed from the gases and vapors by indirect contact with the tar. Byproper regulation a total clean oil or several clean oil fractions maybe collected from the gases as desired.

Where more than one still is employed each still is connected with anumber of retorts. 'I'he hot gases from two or more tiers of retorts maybe combined and passed into each of the stills. 'I'he hot gases frommultiple standpipes connected with four tiers of retorts, for example,can be combined with a hot gasvheader through which the gases pass to astill. The hot gases from more than four tiers or less than four tiersmay be combined to be passed into the still, where desirable.

Where more than one still is employed the gases to be passed througheach of the stills may be separately collected yor the gases from anumber,

of tiers of retorts may be collected in a hot gas header and a portionof the hot gases thus co1- lected passed intoeach of the stills.

The invention may be applied to through retorts or to stop-end retorts,or any type of retort built into a bench in which the retorts arearranged in tiers. When the invention is applied to through retorts agas connection is advantageously made at each end of each of theretorts. One end of the retort is connected with an insulated multiplestandpipe leading to a still and the other end is connected with theordinary hydraulic main. By the proper manipulation of valves in thepipes that connect the same retort with both the hydraulic main and thestill. the gases from this retort may be passed into the still or to theordinary hydraulic main and the ordinary recovery system. With such anarrangement the hot gases and vapors from any number of the retorts maybe passed to one or more of the stills as desired and the balance of thehot retort gases will be passed into the hydraulic main and thence tothe usual condensing system.

The temperature at which the hot coal distillation gases leave a gasretort varies somewhat depending upon the kind of Acoal being distilled,the

coking cycle, etc. Ingeneral the gases leave the retorts at temperaturesin the neighborhood of.

500 C., but the temperature may vary above and below this depending onthe coking conditions and coking cycle. The temperature of the gases issuiliciently high to carbonize tar and form coke when brought intodirect contact with the tar. Therefore, when the gases are employed forthe distillation of tar the tar is sprayed into the gases in the form ofsuch a fine intense spray that the gases are rapidly cooled toapproximately the temperature of the tar and the tar is rapidlydistilled. Such an intense spray of tar is maintained in the still atall times that the heat of the gases is quickly absorbed as sensibleheat in the pitch and vapors produced and as latent heat in the oilvapors resulting from the distillation. The entire still isadvantageously iilled with a ilne intense tar spray and the walls of thestill are washed with the tar so that the accumulation of pitch or cokeon the walls of the still is prevented. The word tar in this patentincludes raw tar, dehydrated tar or stripped tar from which some of themore volatile oils have been removed. i. e. semi-pitch.

Where several stills are employed in series the distillation residuefrom the first still is sprayed into the hot gases in the second stillof the series where it is further distilled and in this manner the taris progressively distilled until pitch of the desired melting point isproduced.

In distilling the tar the flow of the tar and the hot gases may beparallel so that the hottest gases are brought into contact with thecoldest tar, and the tar after being in the still for a period gases maybe admitted to opposite ends of the still in order to take advantage ofthe economies inherent in countercurrent distillation.

The hot gases leaving -a gas retort contain fine particles of suspendedimpurities. These comprise particles of coke, pitch, etc. They can beseparated from the gases only by some thorough cleaning operation, suchas an intensive scrubbing. According to the preferred method of carryingout this invention the gases are sprayed with such an intense spray oftar that entrained impurities are scrubbed from the gases and the gasesas they leave the still are substantially deterred.

It may be desirable to pass the gases and vapors v resulting from thedistillation of tar ,in the hot retort gases, up through a settlingchamber or bailiing chamber before they enter the condensing system inorder to remove entrained particles of tar spray from the gases, so thatthe oils obtained in the condensing system will be clean oilssubstantially free from tarry and pitchy constituents. For this purposea settling chamber or baiiie tower may be provided on each still, orwhere several stills are employed and only one condensing system isprovided, the gases from the several stills may be combined and togetherpassed through the settling chamber or baflie tower before entering thecondensing system.l

The invention will be further described in connection with theaccompanying drawings but it is intended and is to be understood thatthe lnvention is not limited thereto.

In the drawings:

Fig. 1 is a plan view of a gas retort plant equipped with several stillsfor the distillation of tar with parallel ow of the gas retort gasesthrough the stills, and the parallel flow of the tar through the stills;

Fig. 2 is an elevation of Fig. 1;

Fig. 3 is a detail showing a section through one of the stills;

Fig. 4 is a detail vshowing the lvalve arrangement employed forconnecting and disconnecting one of the retorts and the hot multiplestandpipes:

Fig. 5 shows valve means for connecting or disconnecting one of theretorts and the standpipes connected with the hydraulic main;

Fig. 6 is a plan view ofa gas retort plant with a number of stills andparallel flow of the gases through the stills with means for conveyingthe tar through the stills in series;

Fig. 7 is an elevation of Fig. 6; and

Fig. 8 is a section through the first still of the series and thesettling tower.

In the drawings, 5 indicates a bench of through gas retorts. The retorts6 are arranged in tiers of ve retorts each. Standpipes 7 connect each ofthe retorts in the bench with the hydraulic main 8. This main isconnected through the foul main 9 with the condensers 10. Tar andammonia liquor from the hydraulic mainare drawn off into the decanter 11and the tar and ammonia liquor are separately collected in the tanks 12and 13, respectively. A pipe is shown at 14 for supplying ammonia liquorfrom thetank 13 to the hydraulic main. This apparatus may be of theusual type.

At the opposite end of these retorts from the end at which thestandpipes 7 are connected. multiple standpipes 15 are provided, each ofwhich is connected with all of the retorts in two tiers. Several ofthese multiple standpipes connect with a hot gas header 16 and this hotgas header connects the stills 17 with each of the retorts in thesetiers to which the multiple standpipes 15 are connected. Three stills 17are shown.

In each still is a roll 18 or other element of generally cylindricalcontour. It is rotated at high speed on a horizontal axis by the motor19, for example, at a speed of 900 to 1200 R. P. M. By rapid rotation ofthis roll, tar which is supplied to the still is sprayed in the form ofa fine inlense spray up into the hot gases passing through the still.The tar is distilled and the gases are substantially detarred. The pitchproduced is drawn off through the tar trap 19 and the levelling arm 20into a trough 21. Here it is sprayed by a jet of cold water from thepipe 22. This chills and granulates the pitch and the solid pitchproduct is drawn off into the bin 23 Where it is separated from water inany desirable manner.

The hot gases and vapors pass from the stills through the settlingtowers or saturators 25. The tar fed to the still is supplied by theline 26 and sprayed into the tower through the nozzle 27. It

is partially distilled by the hot gases and vaporspassing through thetower or saturator and the distillation residue is drawn off from thebottom of the tower through the line 28 and fed to thestill 17 at theend of the still at which the hot gases enter from the header 16.Bailles 29 and 30 are provided in the saturator to remove entrainedparticles ofspray from the gases so that when cooled the gases whichleave the tower will yield substantially clean oils. The standpipes l5,the hot gas headers 16, the stills 17 and the saturators 25 areadvantageously heavily insulated as shown at 3l.

By closing part or all of the valves 35 connecting the retorts with thestandpipes 7 and the hydraulic main and opening the valves 36 connectingthese retorts with the standpipes 15, the coal distillation gases fromthese retorts will be passed into the stills and will be employed forthe distillation of tar. The intense spray of tar in the stills scrubsthe gases, the tar is distilled and the gases are enriched in oilvapors, and on cooling the gases leaving the stills, clean oil productsare obtained. The flow of tar in the various stills may be independentlyregulated so that pitches of diierent melting points may be producedsimultaneously. Separate condensers may be providcd for each still wherethis is desirable.

`According to the arrangement shown in Figs. 1 and 2 the gases andvapors from all of the stills are collected in the main 40 and pass intothe heat interchanger 41 where they are brought intoy indirect contactwith the incoming tar. The incoming tar is fed through the line 42 andafter leaving the preheater a portion of the preheated tar is suppliedto each of the stills. Heavy clean oils are condensed from the gases inthe preheater and these oils are collected in the tank 43 and representa high boiling oil fraction which may be disposed of as creosote oil.

After leaving the preheater the gases pass to the condenser 43' wherethey are sprayed with Water or ammonia liquor from the pipes 44. Thecondensate together with ammonia liquor is collected in the decanter 45and the ammonia liquor and oils are separately collected in the tanks 46and 47. An exhauster 48 is provided beyond this condenser to draw thegases through the system. This exhauster may be the same exhauster asthat employed for drawing the gases from thehydraulic main through thecondensers 10 and the same system for the recovery of ammonia and lightoils, etc. may be utilized for treating both gases or separate systemsmay be provided. Valves 49 such as the ordinary butterfly valves may beprovided for regulating the flow of gases through each of the stills.

Figs. 6 and 7 show a series of stills in combination with a gas retortplant and means for passing the tar through the stills in series. Thestills \17a may each be connected with a number of retorts 6a. throughthe headers 16a and the standpipes 15a.. Each standpipe is connectedwith all of the retorts in a single tier. A spray of tar may be producedin each still by a roll 18a in the way described in connection withFigs. 1 and 2 and the pitch produced will be drawn 01T through thelevelling arm 20a. The position of this levelling arm controls the depthto which pitch is retained in each still and consequently controls thenature of the tar spray thrown from the roll in each still.

According to the arrangement shown in Figs. 6 and 7, each of the stillsis connected with a h ot gas and vapor main 50 and one settling tower orsaturator 51 is provided for all of the stills. The gases and vapors aresprayed in this saturator with tar supplied through the line 52.Distillation residue from the bottom of the saturator is fed to thestill through the line 53. This tar flows through the stillcountercurrent to the ow of the hot gases which are admitted to thestill from the hot gas header 16a. The partially distilled tar orsemi-pitch produced is drawn ofi into the cup 55 at the same end of thestill as that at which the hot gases enter. A portion of this partiallydistilled tar may be'draw'n off through the line 56 to a separatestorage tank to be used for road-treating purposes or in any otherdesired way. A portion of the tar from this cup 55 is supplied bygravity through the line 57 to the second still of the series. In thedrawings it is shown as passing through the still in a directioncountercurrent to the liow of the hot gases. After further distillationin the still itis drawn oil' into the cup 58. A portion of thesemi-pitch produced may be drawn off to a separate storage tank throughthe line 59.

The last still of the series is supplied by gravity through the line 60and where high melting point pitch is to be produced the semi-pitch fromthe preceding partial distillations is advantageously added to this laststill at the same end of the still at which the hot gases enter, so thatthe hot gases and the pitch will flow through the still in a concurrentdirection. The high melting point pitch produced is drawn off throughthe levellirg arm 20a into the trough 6l where is is met-with a spray ofcold water from the line 62. This chills and granulates the pitch andthe solid pitch lproduct is collected in the bin 63. l

After leaving the hot gas saturator the clean gases and vapors passthrough the heat interchanger 64 where they are brought into indirectcontact with the incoming tar. This tar is fed through the line 65 andafter being preheated in the heat interchanger 64 passes through theline lui) n ammonia liquor and oils are separately collected in thetanks 70 and 71.

An exhauster 72 is provided for drawing the gases through the system andvalves 73 are provided for regulating thetlow of gases through each ofthe stills.

Various modifications of the invention may be employed and existing gasretort y.plants mayf readily be equipped with means for employing theinvention without extensive alterations. By proper manipulation high oilyields may be obtained and oils substantially free from tarry and pitchyingredients may be produced directly.

References to pitch melting points referto melting points determinedbythe method described in Methods of Analysis used in the Coal TarIndustry, by J. M. Weiss in the Journal of Industrial and EngineeringChemistry, vol. 10, No. 10, October 1918, page 817. Boiling points referto boiling points determined by method D-246- of the American Societyfor Testing Materials.

This application is in part -a continuation of my copending application,Serial No. 326,770, filed December 18, 1928. f

I claim:

1.The method of distilling tar by direct contact with hot coaldistillation gases from a bench of gas retorts which comprisescollecting the hot gases to be used for the distillationfrom a pluralityof retorts and combining them, passing the combined gases into a stillat a temperature not greatly below that at which they leavel theretorts, intensely spraying tar to be distilled into the hot gases, soregulating the amount of tar supplied and the intensity of spraying withrespect to the volume and temperature of the hot gases employed fordistillation that almost instantaneous cooling of the gases to asubstantially lower temperature, and rapid heating and distillation ofthe tar are effected, withdrawing distillation residue from the still,and withdrawing the mixed gases and vapors therefrom and cooling them tocondense oils.

2. The method of distilling tar to pitch by direct contact with hot coaldistillation gases from a bench .of gas retorts which comprisescollecting the hot gases to be used for the distillation from aplurality of retorts and` combining them, passing the combined gasesinto a still at a temperature not greatly below that at which they leavethe retorts, spraying tar into the gases Cin the still in the form of aiine intense spray which substantially iills the entire vvapor space ofthe still and washes the walls of the still `so that accumulation ofpitch thereon is prevented, whereby the tar is rapidly distilled topitch, withdrawing the pitch from the still, and withdrawing the mixedgases and vapors therefrom and cooling them to condense oilvapors.

3. The method of distilling tar by direct contact with hot coaldistillation gases from a bench of gas retorts in which the retorts arearranged creased, combining the gases and vapors resultin tiers, whichcomprises collecting the gases from a plurality of the retorts in aplurality of the tiers and forming them into a plurality of hot gasstreams, all while minimizing any drop in the temperature of the gases,introducing each of said streams into a different tar still, bringingtar into direct contact with each stream in each still whereby the taris distilled and the vapor content of the gases is increased, andcombining the gases resulting from the distillation of tar in the stillsand also cooling the gases from the stills so as to recover distillateoils.

4. The method of distilling tar by direct contact with hotcoaldistillation gases from a bench of gas retorts in which the retorts arearranged in tiers, which comprises collecting the gases from a pluralityof the retorts in a plurality of the tiers and forming them into aplurality of gas streams all while minimizing any drop in thetemperature of the gases, introducing each of said gas streams into atar still, passing the tar through the stills in series, bringing thetar into direct contact with each of the gas streams in each of thestills and subjecting it to partial distillation in each of thek stillswhereby the tar is progressively distilled and the oil vapor content ofeach gas stream is increased as it passes through the still.

5. The method of distilling tar by direct contact with hot coaldistillation gases from a bench of gas retorts in which the retorts arearranged in tiers, which comprises collecting the gases from a pluralityof the retorts in a plurality of the tiers and forming them into-aplurality of hot gas streams, all while minimizing any drop in thetemperature of the gases, introducing each of said 1 gas streams into adiiferent tar still, bringing tar into direct contact with the stream ofhot gas passing through each still, whereby the tar is distilled and theoil vapor content of the gas is ining from the distillation of tar in aplurality of the stills and bringing the combined gases and vapors intoindirect heat interchanging relation with the tar to be distilled,whereby the tar is preheated and oils are condensed from the gases.

6. The method of distilling tar with highly heated tar-laden gasesresulting from the distillation of coal in a gas retort which comprisesrepeatedly and continuously and thoroughly spraying the gases with suchan intensive spray of the tar that the tar particles suspended in thegases are effectively removed so that on subsequent coolingsubstantially clean oils are obtained while simultaneously the tar israpidly heated and distilled v and the gases are almost linstantlycooled to a 1 temperature approaching that to which the hydrocarbon isheated, separating entrained spray from the resulting gases and vapors,and cooling the gases and vapors to condense hydrocarbons therefrom inthe form of clean oils.

7. In combination with a gas retort bench in which the retorts arearranged in tiers, an insulated standpipe connected to retorts of one ofsaid tiers, a tar still adapted to contain a small body of tar, a hotgas header for conveying hot fresh 1

